Electric arc-extinguishing apparatus



March 16, 1943. o. c. TRAVER ELECTRIC ARC-EXTINGISHING APPARATUS Filedoct. 2, 194o` CLSSSSXSSX e .Tr-*avec y m.

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chute into which Patented Mar. 16, 1943 ELECTRIC Anc-Exmem'snmcAPPARATUS Oliver C. Travel', Drexel Hill, Pa., to General ElectricCompany York a corporation of New Application october 2, 1940, serialNo. 359,371

.'12 claims. (ciano-141i l My invention relates to electricarc-extinguishing apparatus having particular application to electriccircuit-interrupting devices, such as circuit breakers, lightningarresters, and the like, of the magnetic blow-'out type employing an arcthe arc is directed and extinguished. l

The use of insulating arc chutes in connection with interruptingelectric currents is a wellknown and accepted practice. In general, thearc is forced into the arc chute by suitable means, such as a magneticblow-out coil and is stretched and elongated, thereby increasingthe arcresistance until the arc is extinguished. In'the case of heavy currents,however, this method alone may be insuillcient for the arc may be blownentirely through they chute without being extinguished. f

In a more effective form of arc chute it has been proposed appreciablyto elongate the Varc path within the chute by means of spacedinterleaving ribs or ilns extending from the opposite walls of the chuteso as to form a restricted 'tortuous passage, generally of zigzag form,for

the arc as it proceeds through the chute. The closely confining walls ofthis passage also extract heat from the arc stream, thereby increasingthe resistance of the arc to a further extent and aiding in theinterruption thereof.

It is an object of my invention to provide a new and improvedarc-extinguishing apparatus of the aforesaid type in which theconfiguration of the arc passageway is such as'to increase theinterrupting ability of the apparatus.

It is another object of my invention to provide.

a new and improved arc-extinguishing apparatus including a plurality ofarc chutes serially arranged with respect to said arc.

Incircuit-interrupting devices of the prior art.

- arc chutes of the general type comprised interleaving fins which wereevenly spaced and madel as plates or ribs' of uniform thicknessprojecting perpendicularly from the walls ofk the arc chute. Such adevice is y shown, for example, United States LettersPatent No.2,293,513, Linde, granted August 18, 1942,l and assigned to the sameassigneev as the present application. It is recognized by thoseskilled'ln the artthat the circuitinterrupting ability of anarc-extinguishing device of the type'referred to above is increased whenthe heat transfer between the arc and the arc chute is increased andarrangements have been proposed for obtaining more extensive heattransfer between the arc andthe arc chute'. ySuch an arrangement isdisclosed and extinguishing apparatus.

pose to provide a circuit-interrupting device iny Since arc chutes ofthe interleaving type may be constructed oi? fragile material, such ascfa ceramic nature, the probability of fracture would berelativelygreat, which might make the circuit-interrupting devicepractically useless in so far as its intended purpose is concerned. Iprowhich the' probability of rendering the circuitinterrupting deviceuseless by virtue of fracture of ther fragile arc chute is greatlydecreased.

vide a new and improved circuit-interrupting device comprising aplurality of arc chutes and means for forcing the arc drawn into saidchutes to extinguish the same rapidly. n

Still another object of my invention is to provide a new and improvedelectric circuit-interrupting device including a plurality of arc chutesand fluid-pressure generating means to force said arc into said arcchutes to extinguish the same rapidly.

Further objects and advantages of my invention will become apparent asthe following description proceeds and the features of novelty whichcharacterize my invention will'be `pointed out with particularity in theclaims annexed to and forming a part of this speciilcation.

. For a better understanding of my invention, reference Lmay ber had tothe accompanying drawing in which Fig. l is a schematic diagram partlyin section of an electric circuit-interrupting device embodying myinvention, Figs. 2 and 3 are complete sectional views taken respectivelyon lines 2-2 and 3 3 of Fig. 1, assuming Fig. 1 to be a complete viewalthough actuallyL shown in section in the interest of clearness.v Fig.4 is similarly a view only of the interleaving arc chute taken from line1 4 of Fig. l, and Figs. 5 and 6 are sectional views taken respectivelyon lines 5-5 and 6--6 of Fig. land, except for being sectional views,are similar to Fig. 4.

Referring now to the drawing, I have illustrated mylnventionkspeciflcally as applied to an air circuit breaker of themagnetic blow-out type but lit will be understood by thoseskilled in theart that my invention is equally applicable to lighting arresters, andfluids other than air might also be used successfully. Thecircuit-interrupting device of Fig. 1 is illustrated as comprising apair of relatively movable contacts II and I2 arranged in a suitablearc-extinguishing structure generally indicated at I3 and supported onsuitable insulating means I 4 and I5, which means might, as illustrated,also serve to house the electrical connections leading from contacts andI2 to the associated power circuit, not shown. This circuit maypreferably be connected to stationary contact II through a spirallyarranged blow-out coil I6 which includes a magnetic core I1. Forelectrical and mechanical reasons, blow-out coil I6 is illustrated ascomprising two spiral portions I6' and I6" separated by an insulatingbarrier I8 (Figs. 2 and 3), whereby both the terminals thereof are onthe outside of the spiral. For the purpose of simplifying thedisclosure, the insulation around blow-out coil I 6 has not been shownbut it will, of course, be understood by those skilled in the art thatsuch insulation will be provided and, furthermore, the cross section ofthis blow-out coil will be determined by the amount of current to becarried thereby.

Movable contact I2 may be connected to the other terminal of thecircuit-interrupting device in any well-known manner. Also, any suitablemeans, such as the solenoid shown, may be provided for operating contactI2, and, consequently, producing relative movement between contacts I Iand I2. In the event that the arc-extinguishing device of my inventionis to be used as a lightning arrester, it will be understood thatcontacts I| and I2 will be permanently separated to form a gap acrosswhich an arc will be formed upon the occurrence of a lightning surgeand, consequently, means for producing relative movement betweencontacts II and I2 will notbe re quired.

The arc-extinguishing structure, generally indicated at I3, comprises apair of disk-shaped plates I9 and 20, Figs. 2 and 3, mounted parallelwith one another and between which are'supported the arc chutes to bedescribed hereinafter. These plates engage respectively the ends ofmagnetic core I1. A plurality of arc chutes 2| are supported betweendisk-shaped plates I! and and, as illustrated in Fig. 1, arecircumferentially arranged around blow-out coil II. Preferably, suitableinsulating members 22, Figs. 2 and 3, separate disk-shaped plates I9 and20 from the arc chutes 2| which they support. The arc chutes 2| arespaced from one another by means of triangular inserts 23, 2l, 25, and23, which are'formed of a. suitable insulating material with the inneredges thereof, 23', 24', 25', and 26', respectively, adjacent the arcdrawn in arc-extinguishing structure I3 being formed of an insulatingmaterial of a type preferably composed of a gas-evolving or gas-emittingsubstance, such as horn ber or the like, so as to produce anarc-extinguishing gas when subjected to the heat and other action of thearc. 'I'hese arc chutes 2| are preferably constructed `of a ceramicmaterial and, as illustrated, may be sup ported so as to form a strongunitary structure by being keyed to triangular inserts 23, 2l, 25, and26, as indicated at 21 so as to provide a cylindrical structure with thearc chutes 2| arranged around the circumference thereof suitably spacedfrom one another by virtue of the triangular inserts 23 to 2B. It willbe obvious that, by this arrangement, any one of the fragile are chutes2| of ceramic material might be replaced in the event that it shouldbreak, thereby considerably reducing the cost of repair. Furthermore,the fact that one of the arc chutes I1 was broken would not render thecircuit-interrupting device useless as the remaining arc chutes wouldinterrupt the arc with somewhat decreased emciency.

I have illustrated the arc chutes 2| as all identical in structure butthe inserts 23, 2l, 25, and 2B are diil'erent in that the insertsdesignated by the higher numerals are larger and extend farther into thecylindrical arc-extinguishing structure I3 so that the arc is forcedinto more intimate contact with the gas-evolving portions 23', 24', 25',and 26' thereof as it is extended in length. Incidentally, thesegasevolvingportions 23', 24', 25', and 2l' should preferably bereplaceable as will be understood by those skilled in the art.

A suitable arc runner 2l is circumferentially arranged within thearc-extinguishing structure I3 in such a manner that, as the arc travelsalong the arc runner by virtue of the magnetic forces produced byblow-out coil I3, it is forced into more and more intimate contact withthe gasevolving material 23', 2l', 2l', and 23', respectively.

In order that a suitable fluid blast may be provided to aid blow-outcoil I3 in forcing the arc into arc chutes 2|, the walls of thecylindrical arc-extinguishing structure between arc runner 23 and arcchutes 2| are each preferably covered with a layer of gas-evolvinginsulating material 29. This gas-evolving material is illustrated inFig. 1 as being suitably keyed at 35 at one end thereof to one of thearc chutes 2| while, at the other end thereof, it is keyed at 3| totriangular insert 23. It will be obvious to those skilled in the artthat, instead of keying arrangements 21, 30, and 3|, illustrated in Fig.1, any other fastening means may be utilized which provide a structuresuillciently strong to withstand the forces involved. It will beobserved that the arc chutes 2i, inserts 23, 2l, 25. and 23, andgasevolving material 23 are keyed together as a unitary structure whichis further supported by plates I! and 2l.

The two layers of gas-emitting insulating ma teriai 20 are separatedsufficiently to define a space 32 therebetween, Figs. 2 and 3, for theare, which space leads to the entrances 33, Figs. 1 and 6, of arc chutes2|. This space will be proportioned so as not to impede the arc in itsmovement into are chutes 2| and yet so that sumcient gas is evolved fromthe gas-emitting insulating material 29 so that a blast of huid underpressure aids the blow-out coil I3 in forcing the are into arc chutes 2|In order to decrease the possibility of restriking of the arc, I mayprovide means for displacing the ionized air adjacent contacts II and I2during a circuit-interrupting operation and replacing it with un-ionizedair. In the drawing. I have illustrated an arcuate recess Il cut in eachof the gas-evolving insulating members 23 to ac commodate a movable vane35 which is integrally connected with the means for operating movablecontact I2. The vane 35 and movable contact I2 are shown dotted in Fig.1 in the positions which they assume when the circuit breaker is open.

Each of the arc chutes 2| is arcuate in shape and comprises a pair ofplates preferably composed of arc-resisting material, such as. for.example, an asbestos compound or a suitable arcresisting ceramicmaterial. Each wall of the chute is provided with a plurality ofradially extending rib-like fins or ridges IB and 31, respectively,andthose ridges 38 and 31 are preferably integral with the side walls ofthe arc chutes 2|. As best shown in Figs. 4 and 5, these ridges or finsare saw-toothed in shape kand the projection of the fin is a maximum atthe outer circumference of the circuit breaker structure I3 and chute2i. The ridges of the two parallel plates comprising arc chutes 2i areyso arranged with respect to each other as to be interleaved when theplates are in position, as shown in Fig. 2,

so as to form a zigzag passage 33", as shown in Fig. 4. This passageincreases in length with respect to the are as the arc is driven fartherand farther i-nto the chute, the chute being constructed so that, at theentrance thereof, the passage 33, see Fig. 6, is relatively short, andwhich increases in length while traversing the chute. In Fig. 5, thepassage 33 is shown as longer than the passage 33 of Fig. 6 but shorterthan the passage 33 of Fig. 4. Furthermore, in accordance with myinvention, the interleaving barriers or ridges 36 and 31 are graduallyand progressively thickened vfrom the inner edge of arc chute 2i to theouter edge thereof to effect a gradual squeezing of the arc along itswhole length, thereby forcing the arc into more intimate contact withthe arc chute, consequently i-ncreasing the heat transfer and aiding theinterruption thereof. The arrangement is preferably such that theproduct of the length and the width of the arc path at the entrance ofthe arc chute is substantially equal to this product at the exhaustextremity of the arc chute.

The operation of my improved circuit-interrupting device will now bedescribed with refer-y 1ence to Fig. l. When relative movement betweencontactsril and I2 is produced, an arc is drawn increasing itslengthand, consequently,'also the arc resistance.,y The are also comingin contactv with gas-'emitting 'material- 2 3 causes gas to be evolvedwhichids .theblowout coil' Il in forcing the arc intof the entrance:passage, Fig. 6, of arc chutes 2 The arcalsojciirig into intimatecontact-wlthfthepcrtions 23', 24', 2,5', and 26 formed ofgasevolvingmaterial produces a fluid under relatively highpre'ssurewhich exhausts through 'theiarc chutes 2i as a fluid blast forcing thearcwithJit. As the arc moves through thevarc ;,chutes;2|;; which. areserially arranged witli'respectf to fthe arc, the' arc pathcontinuouslylengthensv in view of the radially extending ribs or iins 36and 31, providing a zigzag path transverse to thenormal direction of arcexpansion. Since the ribs 36 and 31 are gradually thickened toward theouter circumference of the arcuate-shaped arc chutes 2i, the crosssection of the arc path is'gradu'ally decreased and the arc is squeezed'vinto more and more intimate contact with the arc chutes sofas to becooled and, consequently, extinguished in a very short space of time.

Although my invention also inherently ernbodies the unbalanced magneticinteraction of the magnetic forces on the arc so as to force thedwindles down to zero at the inner edge of arc arc against the portionsof the are chute, this reature is broadly claimed in the above-mentionedyBoehne patent.

It shouldbe understood that my invention is not limited`to the specificconstruction and arrangement herein illustrated and that changes andmodifications may occur to those skilled in the art without departingfrom the spirit and scope of my invention. I, therefore, aim in theappended claims to cover all such changes and modications. f

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

l. In an electric arc-extinguishing apparatus comprising an insulatingarc chute into which the arc to be interrupted is directed yhaving sidewalls disposed in closely spaced parallel relationship so as to form anarrow arc space therebetween, saidwalls on the sides facing each otherhaving thereon in projecting relation interleaving ridges extendingsubstantially transversel'y of the pathof said arc, the ridges of onewall being spaced with respect to the interleaving ridges of said otherwall and said ridges being so shaped anddisposed as to provide for thearc a continuously lengthening path between said side walls which iszigzag transversely to the normal direction of arc expansion, saidridges being progressively thickened in the direction of arc expansionto effect a gradual squeezing of the arc along its whole length to forceit into more intimate contact withsaid arc chute to cool the samerapidly. f y y 2. In an electric circuit-interrupting device, thecombination of an insulating arc chute into which the arc to beinterruptedis adapted to be directed having side walls disposed inclosely spaced parallel relationshipy so as to form a narrow arc spacetherebetween, said walls on the sides facing each other having-thereon aplurality of ribs, said ribs being so shaped and disposed and sointerleaved with each other as to provide for the arc a continuouslylengthening path between said side walls which is zigzag transversely tothe normal direction of arcy expension, the transverse spacing betweensaid ribs decreasing in said direction of are expansion to eect agradual squeezingof the arc to force vit into more intimate contact withsaid arc chute 4lio/'and means including gas evolving insulatingmaterial mounted adjacent the entrance to said arc chute so that whensubjected to the heat of said arc gases are evolved which drive the areinto said arc chute to extinguish the same.

3. In an electric circuit-interrupting device, the combination of aninsulating are chute into which the arc to be interrupted is directedhaving side walls disposed in closed spaced parallel relationship so asto form a narrow are space therem between, said walls on the sidesfacing each other having thereon a plurality of saw-tooth shaped fridges. said ridges being so disposed and so interleaved with each otheras to provide for the arc a continuously' lengthening path between saidside walls which is zigzag transversely to the normal direction of arerexpansion, said sawtooth shaped ridges being progressively thiclb` enedin the direction of arc expansion to eiect a gradual squeezing of thearc thereby to increase the heat transfer to said arc chute.

4. In anelectric circuit interrupter including means between which anelectric arc is adapted to be formed, an arc-extinguishing structurecomprising a plurality of arc chutes alternately arranged betweensections of gas-evolving insulating material and serially arranged withrespect to said arc, magnetic means for forcing said arc into said arcchutes and against said gas-evolving insulating material, said arcchutes each comprising a pair of parallel plates having rib-likeprojections of insulating material, magnetic means for forcing said arcinto said arc chutes, a gas-evolving insulating material being disposedadjacent the entrances to said arc chutes so that gas under pressure isproduced when said arc acts on said gas-evolving material to aid saidmagnetic means in forcing said arc into said arc chutes, each oi saidarc chutes comprising a pair of parallel plates having the adjacentfaces thereof serrated,

the serrations being so disposed as to be interleaved with each other soas to provide a continuously lengthening path for said arc which iszigzag transversely to the normal direction of arc expansion.

6. In an electric circuit interrupter including means between which anelectric arc is adapted to be formed, an arc-extinguishing structurecomprising a plurality of arc chutes spaced from one another by sectionsof insulating material, magnetic means for forcing said arc into saidarc chutes, said arc chutes each comprising a pair of parallel plateshaving the adjacent faces thereof serrated, the serrations being sodisposed as to be interleaved with each other so as to provide acontinuously lengthening path for said arc which is zigzag transverselyto the normal direc tion of arc expansion, said serrations beingprogressively thickened in the direction of arc expansion to eilect agradual squeezing of the arc thereby to increase the heat transfer tosaid arc chute.

7. In an electric circuit-interrupting device, the combination of aninsulating arc chute into which the arc to be interrupted is adapted tobe directed having side walls disposed in closely spacedrelationship soas to form a narrow arc space there between, said walls on the sidesfacing each other being so disposed as to provide for the arc acontinuously lengthening path between said side walls,

the spacing be'tween said walls progressively decreasing in thedirection of arc expansion to effect a gradual squeezing of the arc toforce it progressively into more intimate contact with said arc chuteand means including gas evolving insulating material mounted adjacentthe entrance to said arc chute so that when subjected to the heat ofsaid arc gases are evolved which drive the arc into said arc chute toextinguish the same.

8. In an electric circuit-interrupting device, the

combination of an insulating arc chute into which the arc to beinterrupted is directed having side walls disposed in closely spacedrelationship so as to form a narrow arc space therebetween, said wallson the sides facing each other being so disposed as to provide for thearc a continuously lengthening path between said side walls, the spacingbetween said walls progressively decreasing in the direction of arcexpansion to ei'iect a gradual squeezing of the arc to force itprogressively into more intimate contact with saidv arc chute, theproduct of the length and the width of the arc space between said sidewalls at the exhaust extremity of said chute being of substantially thesame order as the product of the length and the width of the arc spaceat the entrance to said arc chute.

9. In an electric circuit interrupter including means between which anelectric arc is adapted to be formed, an arc-extinguishing structurecomprising an arc chute arranged between sections of gas-evolvinginsulating material, and means for moving said arc to the entrance ofsaid arc chute and into active proximity to said gasevolving insulatingmaterial so that gases are evolved therefrom which drive the arc intosaid arc chute to interrupt the same.

l0. In an electric circuit interrupter including means between which anelectric arc is adapted to be formed, an arc-extinguishing structureoomprising a plurality of arc chutes alternately positioned betweensections oi gas-evolving insulating material, and means for moving saidarc to the entrance of said arc chute and into active proximity to saidgas-evolving insulating material so that gases are evolved therefromwhich drive the arc into said arc chutes to interrupt the same.

1l. In an electric circuit interrupter including means between which anelectric arc is adapted to be formed, a circular blow-out means, anarcextinguishing structure comprising a plurality of arc chutes arrangedin an arcuate form about said circular blow-out means which is common tall ot said arc chutes, a plurality of sections of gas-evolvinginsulating material alternately arranged with said arc chutes aroundsaid circular blow-out means, means i'or moving said arc to the entranceof said arc chute and into active proximity to said gas-evolvinginsulating material so that the gases evolved are exhausted through saidchute to drive said arc into said chute for arc-extinguishing purposes.

12. In an electric circuit interrupter including means between which anelectric arc is adapted to be formed, an arc extinguishing structurecomprising an arc chute constructed chieily of refractory material butincluding a minor amount of gas evolving insulating material located inthe regionof the entrance to said arc chute, and means for moving saidarc to the entrance of said arc chute and into active proximity to saidgas evolving insulating material so that gases are evolved therefrom toassist in driving said arc into said chute to extinguish the same.

OLIVER C.

